Looking for Potential Pests

Among perennial grasses, switchgrass (Panicum virgatum L.) has shown great potential as a biofuel crop in South Carolina, with good performances in soils of marginal quality combined with low water and nutrient requirements. Research on this crop is being conducted at the Pee Dee Research and Education Center.

Herbaceous energy plants such as switchgrass have significantly reduced environmental impacts compared to traditional row crops. Perennial grasses can reduce erosion and runoff, increase incorporation of carbon in the soil and reduce the use of pesticides compared to annual crops. With a dense canopy and extensive root system, switchgrass can replace soil carbon that became depleted by years of row crop production. As an additional environmental benefit, switchgrass also offers a valued wildlife habitat in particular for birds, and also for some species of reptiles, invertebrates, amphibians and mammals because of the canopy structure of such tall grasses.

Insects, however, have only been sparsely studied in switchgrass. A study was initiated in 2007 at the Pee Dee REC to determine the impact of herbivores on switchgrass yield and to identify potential pest species. In addition, insect diversity is being monitored and associated with changes in weed diversity as the switchgrass plant grows. Weeds were abundant during the establishment year in 2007. In 2008 and 2009, switchgrass growth was more rapid in the early spring, which outcompeted most weed species.

With major shifts in weed diversity, substantial changes in insect diversity were recorded. Insect injury has thus far been limited to sporadic grasshopper feeding.